Medical sponges, and particularly neurological sponges, commonly comprise a fibrous web, the fibers of which may be cotton, rayon, polyester or other synthetic or a combination of these. The fibers are bonded one to another by mechanical and/or chemical bonds, either with or without bonding additives. Neurological sponges, generally are of two types, strung and unstrung. In the strung sponges the absorbent web commonly is relatively small, ranging from about 1/4 inch square upwards. Most such sponges are less than about 3 inches in length and about 3 inches wide. The webs commonly are of about 1/32 inch thick. The strung sponges have attached thereto one or two strings, commonly a textile thread having one of its ends anchored to the web and the remainder of the string extending from the web to serve as a locator element. The unstrung sponges most often are larger than the strung sponges, ranging up to 6 inches in length and 3.5 inches in width. These sponges have no depending string attached thereto.
Neurological sponges are employed for absorbing blood and body fluids, but most frequently are saturated with saline or other solution and used to protect tissue or applied to the tip of a suction device for protecting the tissue when suction is applied.
In the course of a surgical procedure, the medical sponges are supplied to the operating room table in units of 10 and are carefully counted before and after use. Because absorbent sponges very closely resemble tissue when the sponge is soaked with blood, it is at times difficult to distinguish the small blood-soaked sponge from the surrounding body tissue. Thus, it is common practice to attach to the sponge a locator string, commonly about 12 inches in length, of a textile material, for example, such string being kept at all times outside the surgical incision so that the presence of the sponge may be readily noted through observing the string. These sponges further are provided with a separate and distinct x-ray opaque element fixed to the sponge in a manner as prevents its dislodgement. In the event the count of the sponges following the surgery indicates that one or more of the sponges is missing and a search of the operating room fails to locate the missing sponge, while the patient is still in the operating room, a portable x-ray unit may be brought in and the surgical site x-rayed in an attempt to determine whether the sponge has been left inside the patient.
Heretofore, neurological sponges have been provided with one or more x-ray opaque elements comprising a polyvinylchloride or polypropylene impregnated with barium sulfate. The prior art teaches attachment of such element(s) to the web by heat bonding or stitching of the element to the web. These same prior art sponges also may be provided with a separate locator string which is either heat bonded or stitched to the web. One such locator string in the prior art is a polyester textile yarn which is heat bonded to the web employing ultrasonic welding techniques. These prior art strings are not radiopaque.
One of the major problems of the prior art neurological sponges is that the small size of the web dictates that the element be no longer in length than the longest dimension of the web. The width of the element desirably is kept as small as possible so as to not reduce the absorptive area of the sponge. It will be appreciated that in the smaller sponges, the area of bond between the x-ray detectable element and the web can occupy a very substantial percentage of one surface of the web. Such small x-ray detectable elements of the prior art make the sponge most difficult to locate with an x-ray unit. This is especially true when it is recalled that the x-ray unit used in an operating room is a portable unit and therefore commonly does not have the high resolution that is desirable when seeking small radiopaque objects. Still further, should the prior art sponge be located inside the patient and oriented "on edge" as presented to the X-ray unit, or behind a bony protuberance, etc. the small size of the x-ray detectable element may cause it to go undetected.
Further, because of the sensitive nature of brain tissue, the presence of the X-ray detectable element in or on a neurological sponge cannot be rough or physically irritating and cannot appreciably detract from the pliability of the sponge especially when wetted. In the prior art it has been suggested to use soft and pliable vinyl or polypropylene-based elements that are impregnated with barium sulfate as X-ray detectable elements. This material is rubbery, stretches readily, and has relatively little tensile strength when formed into thin strips or monofilaments. When bonded to a fibrous pad, however, the monofilamentary nature of the element flattens and stiffens with the result that the sponge loses an appreciable portion of its flexibility. To be effective as a radiopaque element, the size of the element must be sufficient to develop a detectable image. Thus, in the prior art the size of the monofilamentary elements and its expanded, flattened configuration when bonded to the web has both consumed an undesirably large percentage of the area of the web and introduced undesirable stiffness to the web. This is particularly true when the bond of the element to the pad is effected by ultrasonic welding as employed in the prior art, or when the element is in a continuous unitary form.
In larger sponges, e.g. laparotomy gauze sponges, the prior art has included a hollow tubular sheath loop element housing a monofilament of radiopaque material attached to one corner of the sponge and serving as a retrieval loop, plus as an aid in detecting the sponge with a x-ray unit. Such sheaths are relatively bulky and are themselves of a diameter that is equal to or greater than the small neurosponges. In any event, such loops are too large, too stiff, and too abrasive for use with neurosponges. They are attached to the gauze sponge by stitching which is generally unacceptable in neurosponges.
Accordingly, it is an object of the present invention to provide a medical sponge, particularly of the neurological class, which is more readily detectable when subjected to X-ray examination. It is another object of the present invention to provide a medical sponge including an X-ray detectable element and a locator string in which the absorptive area of the sponge is maximized. It is another object of the present invention to provide a novel locator string for surgical devices.